The Ocean Waterfall Dam--Counter-Intuitive Reality

What if instead of building more dams on rivers and streams to generate electricity, we built a 10 mile long, 800ft deep 350ft wide, ultra-modified dam in the Atlantic ocean about 5 miles beyond the three mile limit off the coast of Norfolk, Virginia?

Picture the Grand Coulee Dam, which since 1941, helped to reshape the Northwest with cheap
electricity, it generates 6.5 x 109
watts..=6500 megawatts..=6.5 million kilowatts. It is also the largest concrete structure ever built. US households use on average about 2 kilowatts of electricity, so the Grand Coulee Dam can power 3.25 million such homes.

Currently, approximately 11,200 TeraWatthrs/yr of primary energy is required to meet total U.S. electrical demand. An ocean waterfall dam could generate 1/3 to 2/3s of that requirement.

So let's design a steel and concrete structure along the same lines. Float it into place like an oil rig, attach power lines, connect them to a distribution hub in Norfolk.

This ocean Waterfall could provide hydropower for the entire East Coast to the Mississippi River. This form of hydropower would be continuous, cheap, green and, could potentially replace all or most carbon emitting forms of energy production which would ensure its profitability.

Surely, if we can send mammoth machines into space we can build and float mammoth structures in our oceans. Let's setaside about $5 billion for a three year effort and treat the project like a JFK challenge and instead of going to the moon we save our planet earth by using the most readily available source of energy we have.